scholarly journals Impact of the Particle Diameter on Ion Cloud Formation from Gold Nanoparticles in ICPMS

2018 ◽  
Vol 90 (17) ◽  
pp. 10271-10278 ◽  
Author(s):  
Joshua Fuchs ◽  
Maryam Aghaei ◽  
Tilo D. Schachel ◽  
Michael Sperling ◽  
Annemie Bogaerts ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Particle Diameter ◽  
Cloud Formation ◽  
Ion Cloud

scholarly journals Effect of Particle Diameter and Surface Composition on the Spontaneous Fusion of Monolayer-Protected Gold Nanoparticles with Lipid Bilayers

Nano Letters ◽  
2013 ◽  
Vol 13 (9) ◽  
pp. 4060-4067 ◽  
Author(s):  
Reid C. Van Lehn ◽  
Prabhani U. Atukorale ◽  
Randy P. Carney ◽  
Yu-Sang Yang ◽  
Francesco Stellacci ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Lipid Bilayers ◽  
Surface Composition ◽  
Particle Diameter

scholarly journals Controlled Synthesis of Gold Nanoparticles UsingAspergillus terreusIF0 and Its Antibacterial Potential against Gram Negative Pathogenic Bacteria

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Eepsita Priyadarshini ◽  
Nilotpala Pradhan ◽  
Lala B. Sukla ◽  
Prasanna K. Panda
Keyword(s):  
Gold Nanoparticles ◽  
Pathogenic Bacteria ◽  
Particle Diameter ◽  
Weight Fraction ◽  
Xrd Analysis ◽  
Controlled Synthesis ◽  
Chloroauric Acid ◽  
Gram Negative ◽  
Fungal Extract ◽  
Vis Spectroscopy

Biosynthesis of monodispersed nanoparticles, along with determination of potential responsible biomolecules, is the major bottleneck in the area of bionanotechnology research. The present study focuses on an ecofriendly, ambient temperature protocol for size controlled synthesis of gold nanoparticles, using the fungusAspergillus terreusIF0. Gold nanoparticles were formed immediately, with the addition of chloroauric acid to the aqueous fungal extract. Synthesized nanoparticles were characterized by UV-Vis spectroscopy, TEM-EDX, and XRD analysis. Particle diameter and dispersity of nanoparticles were controlled by varying the pH of the fungal extract. At pH 10, the average size of the synthesized particles was in the range of 10–19 nm. Dialysis to obtain high and low molecular weight fraction followed by FTIR analysis revealed that biomolecules larger than 12 kDa and having –CH, –NH, and –SH functional groups were responsible for bioreduction and stabilization. In addition, the synthesized gold nanoparticles were found to be selectively bactericidal against the pathogenic gram negative bacteria,Escherichia coli.

scholarly journals Predicting the influence of particle size on the glass transition temperature and viscosity of secondary organic material

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Markus Petters ◽  
Sabin Kasparoglu
Keyword(s):  
Particle Size ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Melting Point ◽  
Critical Role ◽  
Particle Diameter ◽  
Cloud Formation ◽  
Melting Point Depression ◽  
Wide Range

Abstract Atmospheric aerosols can assume liquid, amorphous semi-solid or glassy, and crystalline phase states. Particle phase state plays a critical role in understanding and predicting aerosol impacts on human health, visibility, cloud formation, and climate. Melting point depression increases with decreasing particle diameter and is predicted by the Gibbs–Thompson relationship. This work reviews existing data on the melting point depression to constrain a simple parameterization of the process. The parameter $$\xi $$ ξ describes the degree to which particle size lowers the melting point and is found to vary between 300 and 1800 K nm for a wide range of particle compositions. The parameterization is used together with existing frameworks for modeling the temperature and RH dependence of viscosity to predict the influence of particle size on the glass transition temperature and viscosity of secondary organic aerosol formed from the oxidation of $$\alpha $$ α -pinene. Literature data are broadly consistent with the predictions. The model predicts a sharp decrease in viscosity for particles less than 100 nm in diameter. It is computationally efficient and suitable for inclusion in models to evaluate the potential influence of the phase change on atmospheric processes. New experimental data of the size-dependence of particle viscosity for atmospheric aerosol mimics are needed to thoroughly validate the predictions.

scholarly journals Synthesis and Characterisation of Core-shell Gold Nanoparticles

2021 ◽  
Author(s):  
◽  
Michelle Jane Cook
Keyword(s):  
Gold Nanoparticles ◽  
Particle Diameter ◽  
Synthetic Methods ◽  
Ex Situ ◽  
Core Shell ◽  
Silica Spheres ◽  
Final Particle ◽  
Resonance Effects ◽  
Stable Substrate ◽  
Shell Particles

<p>Technology developed at Victoria University of Wellington by Professor James H. Johnston and Dr Kerstin Lucas allows for the colouring of high quality wool fibres using spherical gold nanoparticles. Gold nanoparticles have interesting colours and optical properties due to surface plasmon resonance effects and, using this technology, a boutique range of colours can be imparted onto wool fibres. The colour of gold nanoparticles is determined by their size and shape, hence the colour range achievable using spherical nanoparticles is limited to those obtained by changing the particle diameter and degree of aggregation of these particles. This limitation can be overcome by using gold nanoparticles of different shapes in conjunction with other materials. This research details the synthesis and characterisation of gold nanoshells on spherical silica cores and their use for the colouring of wool. Silica cores were used in this research as they are reasonably chemically inert and so serve as a stable substrate for the gold shells. Silica spheres are also easily prepared in a manner that allows control over the final particle diameter.  Several syntheses of these core-shell particles have been previously devised however they are not suitable for commercial use. Such syntheses involve many time-consuming steps, high temperatures or light-sensitive reagents. Synthetic methods set out in this research involve a novel in-situ seeding of gold nanoparticles for the growth of the shells eliminating the step of growing gold nanoparticles ex-situ commonly involved in other synthetic schemes. The need for light-sensitive reducing agents is eliminated by the use of other reductants such as sodium borohydride and hydroxylamine. All steps of the synthetic schemes are carried out at less than 100 °C. Several methods of synthesising core-shell particles are outlined in this research, which achieved varying degrees of success. Many syntheses investigated successfully produced core-shell particles but also left many silica spheres without the desired gold shell coating. This was not a problem for the proposed application of colouring wool. As silica is easily dispersed in water and does not have the same affinity to bind to wool as gold does, the silica spheres without gold shells simply wash off after colouring. This allowed the core-shell particles synthesised in this research to be successfully used to colour wool fibres and achieve a shade of purple not previously obtained using the earlier methodologies.</p>

scholarly journals New particle formation and its effect on CCN abundance in the summer Arctic: a case study during PS106 cruise

2019 ◽  
Author(s):  
Simonas Kecorius ◽  
Teresa Vogl ◽  
Pauli Paasonen ◽  
Janne Lampilahti ◽  
Daniel Rothenberg ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Negative Ions ◽  
Particle Formation ◽  
Number Concentration ◽  
Cloud Formation ◽  
The Arctic ◽  
New Particle Formation ◽  
Nucleation Mode ◽  
Particle Formation And Growth

Abstract. In a warming Arctic the increased occurrence of new particle formation (NPF) is believed to originate from the declining ice coverage during summertime. Understanding the physico-chemical properties of newly formed particles, as well as mechanisms that control both particle formation and growth in this pristine environment is important for interpreting aerosol-cloud interactions, to which the Arctic climate can be highly sensitive. In this investigation, we present the analysis of NPF and growth in the high summer Arctic. The measurements have been done on-board Research Vessel Polarstern during the PS106 Arctic expedition. Four distinctive NPF and subsequent particle growth events were observed, during which particle (diameter in a range 10–50 nm) number concentrations increased from background values of approx. 40 up to 4000 cm-3. Based on particle formation and growth rates, as well as hygroscopicity of nucleation and the Aitken mode particles, we distinguished two different types of NPF events. First, some NPF events were favored by negative ions, resulting in more-hygroscopic nucleation mode particles and suggesting sulfuric acid as a precursor gas. Second, other NPF events resulted in less-hygroscopic particles, indicating the influence of organic vapors on particle formation and growth. To test the climatic relevance of NPF and its influence on the cloud condensation nuclei (CCN) budget in the Arctic, we applied a zero-dimensional, adiabatic cloud parcel model. At an updraft velocity of 0.1 m s-1, the particle number size distribution (PNSD) generated during nucleation processes resulted in an increase of the CCN number concentration by a factor of 2 to 5, compared to the background CCN concentrations. This result was confirmed by the directly measured CCN number concentrations. Although particles did not grow beyond 50 nm in diameter and the activated fraction of 15–50 nm particles was on average below 10 %, it could be shown that the sheer number of particles produced by the nucleation process is enough to significantly influence the background CCN number concentration. It implies that NPF can be an important source of CCN in the Arctic. However, more studies should be conducted in the future to understand mechanisms of NPF, sources of precursor gases and condensable vapors, as well as the role of the aged nucleation mode particles on Arctic cloud formation.

scholarly journals Technical note: optical extinction coefficient of polydisperse spherical gold nanoparticles in water

2017 ◽  
Vol 12 (4) ◽  
Author(s):  
Jia Cherng Chong ◽  
Lee Siew Ling ◽  
Noriah Bidin
Keyword(s):  
Gold Nanoparticles ◽  
Extinction Coefficient ◽  
Spectral Characteristics ◽  
Particle Diameter ◽  
Resonance Wavelength ◽  
Dipole Approximation ◽  
Technical Note ◽  
Particle Sizes ◽  
Optical Extinction ◽  
Plasmon Resonance Peak

The extinction coefficients of polydispersed gold nanoparticles up to σ = 360 nm were computed via exact solution of Mie theory. A narrow extinction peak around 520 nm occurs for mean particle sizes <d> within dipole approximation limit. Spectral characteristics for extinction coefficient computed based on increasing mean particle sizes, degree of polydispersity, composition ratio of bimodal size distributions and changes in dispersant temperature are compared. As mean particle sizes increases, the plasmon resonance peak red-shifts and broadens skewing towards infrared. Increasing polydispersity on mean particle diameter beyond dipole approximation limit decreases peak extinction coefficient values. Increasing temperature from ambient to boiling changes the peak extinction coefficient intensity value by an order of 10^-13 while resonance wavelength remains unchanged.

scholarly journals Size-resolved cloud condensation nuclei concentration measurements in the Arctic: two case studies from the summer of 2008

2015 ◽  
Vol 15 (23) ◽  
pp. 13803-13817 ◽  
Author(s):  
J. Zábori ◽  
N. Rastak ◽  
Y. J. Yoon ◽  
I. Riipinen ◽  
J. Ström
Keyword(s):  
Cloud Condensation Nuclei ◽  
Measurement Data ◽  
Particle Diameter ◽  
Cloud Formation ◽  
The Arctic ◽  
Research Station ◽  
Condensation Nuclei ◽  
Air Masses ◽  
The Difference ◽  
Measurement Period

Abstract. The Arctic is one of the most vulnerable regions affected by climate change. Extensive measurement data are needed to understand the atmospheric processes governing this vulnerability. Among these, data describing cloud formation potential are of particular interest, since the indirect effect of aerosols on the climate system is still poorly understood. In this paper we present, for the first time, size-resolved cloud condensation nuclei (CCN) data obtained in the Arctic. The measurements were conducted during two periods in the summer of 2008: one in June and one in August, at the Zeppelin research station (78°54´ N, 11°53´ E) in Svalbard. Trajectory analysis indicates that during the measurement period in June 2008, air masses predominantly originated from the Arctic, whereas the measurements from August 2008 were influenced by mid-latitude air masses. CCN supersaturation (SS) spectra obtained on the 27 June, before size-resolved measurements were begun, and spectra from the 21 and 24 August, conducted before and after the measurement period, revealed similarities between the 2 months. From the ratio between CCN concentration and the total particle number concentration (CN) as a function of dry particle diameter (Dp) at a SS of 0.4 %, the activation diameter (D50), corresponding to CCN / CN = 0.50, was estimated. D50 was found to be 60 and 67 nm for the examined periods in June and August 2008, respectively. Corresponding D50 hygroscopicity parameter (κ) values were estimated to be 0.4 and 0.3 for June and August 2008, respectively. These values can be compared to hygroscopicity values estimated from bulk chemical composition, where κ was calculated to be 0.5 for both June and August 2008. While the agreement between the 2 months is reasonable, the difference in κ between the different methods indicates a size dependence in the particle composition, which is likely explained by a higher fraction of inorganics in the bulk aerosol samples.

scholarly journals Gold nanoparticles from Celastrus hindsii and HAuCl4: Green synthesis, characteristics, and their cytotoxic effects on HeLa cells

2021 ◽  
Vol 10 (1) ◽  
pp. 73-84
Author(s):  
Xuan-Truong Mai ◽  
Minh-Chien Tran ◽  
Anh-Quan Hoang ◽  
Phuc Dang-Ngoc Nguyen ◽  
Thi-Hiep Nguyen ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Green Synthesis ◽  
Hela Cells ◽  
Particle Diameter ◽  
Spherical Shape ◽  
Natural Antioxidants ◽  
Cytotoxic Effects ◽  
Au Nps ◽  
Transmission Electron ◽  
Dose Dependent

Abstract The extract from Celastrus hindsii (C. hindsii), a plant that naturally grows in the forests of several provinces of Vietnam, has been traditionally used as an alternative medicine for the treatment of inflammation because of its anticancer and antitumor properties. This study reported the green synthesis of stable gold nanoparticles (Au-NPs) derived from HAuCl4 using the extract of C. hindsii as reducing and capping agents. Their particle size could be controlled by adjusting the ratio of the extract to HAuCl4 solution used (1.25%, 2.5%, 3.75%, 5.0%, and 6.25%). The optimal ratio of the extract was 3.75% (Au-NPs-3.75%). The X-ray powder diffraction analysis demonstrated that the Au-NPs was successfully synthesized. Fourier-transform infrared spectroscopy result indicated the possible presence of phenolic acids and flavonoids (acting as reducing agents and potential natural antioxidants). Transmission electron microscopy images showed that the particle diameter of Au-NPs-3.75% varied between 13 and 53 nm (average: ∼30 nm) in its spherical shape. The biosynthesized Au-NPs-3.75% exhibited dose-dependent cytotoxicity against HeLa cells, and the inhibitory concentration (IC50) was 12.5 µg/mL at 48 h. Therefore, Au-NPs that were synthesized from environmentally friendly method without the presence of potentially toxic chemicals were highly possible in biomedical applications.

scholarly journals Synthesis and Characterisation of Core-shell Gold Nanoparticles

2021 ◽  
Author(s):  
◽  
Michelle Jane Cook
Keyword(s):  
Gold Nanoparticles ◽  
Particle Diameter ◽  
Synthetic Methods ◽  
Ex Situ ◽  
Core Shell ◽  
Silica Spheres ◽  
Final Particle ◽  
Resonance Effects ◽  
Stable Substrate ◽  
Shell Particles

<p>Technology developed at Victoria University of Wellington by Professor James H. Johnston and Dr Kerstin Lucas allows for the colouring of high quality wool fibres using spherical gold nanoparticles. Gold nanoparticles have interesting colours and optical properties due to surface plasmon resonance effects and, using this technology, a boutique range of colours can be imparted onto wool fibres. The colour of gold nanoparticles is determined by their size and shape, hence the colour range achievable using spherical nanoparticles is limited to those obtained by changing the particle diameter and degree of aggregation of these particles. This limitation can be overcome by using gold nanoparticles of different shapes in conjunction with other materials. This research details the synthesis and characterisation of gold nanoshells on spherical silica cores and their use for the colouring of wool. Silica cores were used in this research as they are reasonably chemically inert and so serve as a stable substrate for the gold shells. Silica spheres are also easily prepared in a manner that allows control over the final particle diameter.  Several syntheses of these core-shell particles have been previously devised however they are not suitable for commercial use. Such syntheses involve many time-consuming steps, high temperatures or light-sensitive reagents. Synthetic methods set out in this research involve a novel in-situ seeding of gold nanoparticles for the growth of the shells eliminating the step of growing gold nanoparticles ex-situ commonly involved in other synthetic schemes. The need for light-sensitive reducing agents is eliminated by the use of other reductants such as sodium borohydride and hydroxylamine. All steps of the synthetic schemes are carried out at less than 100 °C. Several methods of synthesising core-shell particles are outlined in this research, which achieved varying degrees of success. Many syntheses investigated successfully produced core-shell particles but also left many silica spheres without the desired gold shell coating. This was not a problem for the proposed application of colouring wool. As silica is easily dispersed in water and does not have the same affinity to bind to wool as gold does, the silica spheres without gold shells simply wash off after colouring. This allowed the core-shell particles synthesised in this research to be successfully used to colour wool fibres and achieve a shade of purple not previously obtained using the earlier methodologies.</p>

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